1. Field of the Invention
The present invention relates to a process and an apparatus for forming films, up to several microns in thickness, on substrates by the combination of ion implantation and vapor deposition.
2. Description of the Prior Art
It is known to form a film on the surface of various substrates, such as steel plates, tools (drills, tips, bits, etc.) and rollers, to give higher corrosion resistance or improved hardness to the substrate.
Known film forming processes for this purpose include vacuum evaporation, sputtering and ion plating (U.S. Pat. No. 3,793,179).
The vacuum evaporation process is advantageous in forming films at a high velocity but has the drawback that the films formed have poor adhesion to the substrates. For example, when strip steel is coated with aluminum and thereafter subjected to press work or like process, the coating or film is likely to peel off.
The sputtering process has the serious drawback of forming films at a low velocity.
The ion plating process rapidly forms films which have stronger bonds with the substrates than those provided by the vacuum evaporation process, but the bond strength still remains to be fully improved.
On the other hand, the ion implantation process is known as a surface modifying technique although it is not a film forming process. By the ion implantation process, physical, chemical condition of near-surface layer can be modified to a depth of hundreds of angstroms to thousands of angstroms from the surface.